Lecture 2 Flashcards
How many neurons in the CNS?
100 billion
What are the 4 key components of typical neurons?
- Soma (cell body)
- Dendrites
- Axon
- Nucleus
How many types of neurons are there? why?
many
because they are specialized for the type of information they’re processing
different types found in different areas
how does info flow through a neuron?
comes in through the dendrites, integrated in the soma, then a decision is made about whether to fire an action potential through the axon
Can changes to the nucleus be short term or long term?
short (electrical )and long term (genetic expression)
What can input from dendrites to the nuclear result in?
either an electrical signal, or changes in gene expression
What can input from dendrites to the nuclear result in?
either an electrical signal, or changes in gene expression
Which pat of the neuron has the genetic material?
nucleus
What are the main functions of glial cells?
- maintain ionic composition of neurons
- modulate the rate of nerve cell propogation (make speed of transmission down an axon e.g. meylein)
- modulate synaptic function through uptake and metabolism of neurotransmitters
- act as scaffolding for neurons during development (make sure neurons are where they are supposed to be and don’t move around)
- repair neural injury + fighting off infections
3 types of Glial cells
- Astrocytes
- Oligodendrocytes
- Mictroglia
Oligodendrocytes are responsible for
myelin sheath
Glial cells are NOT involved in?
electrical signalling
Why is it that neurons are able to communicate electrical signals?
the separation of positively and negatively charged isons across the semi permeable membrane of the neuron
- this results in a potential difference in charge (voltage) across the membrane, which is know as the resting membrane potential
What is the typical resting membrane potential?
-40 to -90 mV
Describe the structure of a membrane?
A lipid bilayer of cells that is hydrophobic (repels water)
- this layer repels
Has membrane spanning protein channels for specific ions
why are the heads of the channels sticking out? (lipid bilayer)
describe the water versus lipid separation and how it makes the membrane semi permeable
*** this is referring to hydrophobic layer and hydrophilic layer + specialize protein channels
they are composed of different things at different sides
the heads of the layer are going to point towards the water end and awar from the fat ends versus the heads like like water point
what are the different changes to voltage that occur
- Hyperpolarization
- Depolarization
- Threshold potential
what is threshold potential?
point at which the neuron becomes sufficiently depolarized to result in an action potential
When do neurons fire/why
other neurons are having a hyperolarizing or depolarizing effect on the neuron, if the cumulative effects of this cause it to reach the threshold potential then the neuron ‘fires’
When do neurons fire/why
other neurons are having a hyperolarizing or depolarizing effect on the neuron, if the cumulative effects of this cause it to reach the threshold potential then the neuron ‘fires’
which type of charge can result in depolarization?
positive charge
which type of charge can result in depolarization?
positive charge (idk if this is true because the inside of the cell is negative and then does depolarization make it more negative or positive? check in textbook)
What happens when depolarization reaches the threshold?
what is this called?
surge of positive charge in the neuron
called an action potential